1. Selection Criteria Properties Availability Cost Manufacturability
Most designers select materials considering
Properties
Availability
Cost
Manufacturability

2. Properties Mechanical
Yield strength (ductile) / Ultimate strength (brittle)
Fatigue (endurance limit)
Stiffness or rigidity (modulus of elasticity)
Hardness (Rockwell, Brinell)
Impact strength (fracture toughness)
Toughness (sharpy test)
Ductility (% reduction is area)
Hardenability
Creep (elevated temperature properties)
High/Low temperature properties
Wear characteristics

3. Properties Physical Chemical Toxicity Resistance to radiation
Density
Electrical properties
Thermal properties (conductivity)
Magnetic
Melting point
Thermal expansion
Flamability
Optical
Chemical
Corrosion resistance
Oxidation resistance
Toxicity
Resistance to radiation
Resistance to elements
Dimensional
Dimensional stability
Surface finish

4. Availability Important questions:
Is the supply plenty, stable, and predictable
Is the material available in the desired form?
Gage 10 sheets of 304L stainless steel?
Do we have to order 100,000 lbs?
Is the material available from company-certified vendors and multiple suppliers?

5. COST The primary factor in material selection in industry
Comparative cost of engineering metals per pound
Hook design: Tungsten
In school: Properties important / cost no issue
In industry: Cost also very important

6. COST
Cost per volume may be a better choice. The following table is $/in3

7. Other Cost Factors
What is the cost of material in relation to the production cost or selling price?
Is it an orbiting satellite or a hammer?
What is the production volume?
A one of a kind design, or Garden Weasel?
What are the primary and secondary manufacturing processes?

8. Manufacturability Primary processes Forming
Rolling (hot or cold) + forging + upsetting + bending + drawing
Machining
Turning + milling + drilling + broaching + sawing
Casting
Sand casting, investment casting, die casting
Welding
Laser cutting + water jet cutting
PM technology

9. Manufacturability Secondary processes Forming Finish forming Machining
Turning + milling + reaming + grinding + lapping + honing
Heat treatment
Deburring
Plating + coating

10. Manufacturing Machinability Weldability Formability, bendability
Cutting forces, chip formation, hardness, work hardening
Weldability
Heat affected zone, brittleness, distortion, oxidation, cracking
Methods, setups
Formability, bendability
Ductility, strength, hardness
Castability
Melting point, runniness, minimum thickness
Heat treatment
Hardenability

11. Designer’s Choices Know about the properties of a few carbon steels
Know about the properties of a few cast irons
Class 20, Class 60, Ductile
Know about the properties of a few alloy steel
4140, 4340, 9310
Know about the properties of a few tool steels
01, A2, D2, S1, H13, M2
Know about the properties of a few stainless steels
304, 304, 316,420,440C, 17-4 PH

12. Designer’s Repertoire
Know about the properties of a few Aluminum alloys:
3003, 5052, 6061, 7075
Know about the properties of a few nickel alloys:
Monel, Inconel
Know about the properties of a few copper alloys:
C36000 yellow brass, C52100 phosphor bronze
Know about the properties of a few titanium alloys
Know about the properties of a few Magnesium alloys

13. Designer’s Repertoire
Know about the properties of a few ceramics
Aluminum oxides
Silicon nitride / Silicon carbide
Cemented carbides
Carbon products
Ceramic coatings (Chromium oxide, Tungsten carbide)
Know about the properties of a few plastics:
Polyethylene / Polyimides / Polyamides
Polycarbonate
PVC /ABS
Nylons
Elastomers

14. Example Bolt tester material selection Criteria for selection:
High strength to weight ratio
High strength in tensile (bending) condition
Some Toughness (ability to absorb impact load)
Rigidity
Manufacturability (and possibly weldability)
Availability in plate form
Cost

15. Choices a-ksi b c d e f g Rating 1040HR 42 25% 30 $ 4 1030CD 64 -
a-ksi b c d e f g
Rating
1040HR 42
25% 30 G $ 4
1030CD 64 -
1095HR 66 9% 5
4140 ann 61
26% $$
Class60 60
Poor 15 E
A47 32
10% 3 52
11%
4340 ann 68
22%
4340 QT
215
12% P ?
$$$ 9
304 ann 40
60% 27
$$$$
538 (C)
290
$$$$$ 8
7075 TC 73
10.4
G (ann)

16. Selection
My choices 
4340 or 4140 in anneal condition with subsequent HT
ASTM 538 Grade C or any other available grade